[PATCH 1/1] drm: mxsfb: Fix NULL pointer dereference

[Alexander Stein]

Do not deference the NULL pointer if the bridge does not return a
bridge state. Assume a fixed format instead.

Fixes: commit b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")
Signed-off-by: Alexander Stein <alexander.stein at ew.tq-group.com>
---
This can happen if a "ti,sn75lvds83", "lvds-encoder" bridge is attached
to it. atomic_get_input_bus_fmts is only implemented for the
lvds-decoder case.

 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index 0655582ae8ed..4cfb6c001679 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -361,7 +361,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
 		bridge_state =
 			drm_atomic_get_new_bridge_state(state,
 							mxsfb->bridge);
-		bus_format = bridge_state->input_bus_cfg.format;
+		if (!bridge_state)
+			bus_format = MEDIA_BUS_FMT_FIXED;
+		else
+			bus_format = bridge_state->input_bus_cfg.format;
+
 		if (bus_format == MEDIA_BUS_FMT_FIXED) {
 			dev_warn_once(drm->dev,
 				      "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
-- 
2.25.1